core,systemctl: add bus API to retrieve processes of a unit

This adds a new GetProcesses() bus call to the Unit object which returns an
array consisting of all PIDs, their process names, as well as their full cgroup
paths. This is then used by "systemctl status" to show the per-unit process
tree.

This has the benefit that the client-side no longer needs to access the
cgroupfs directly to show the process tree of a unit. Instead, it now uses this
new API, which means it also works if -H or -M are used correctly, as the
information from the specific host is used, and not the one from the local
system.

Fixes: #2945

1 files changed, 27 insertions, 0 deletions

diff --git a/src/shared/bus-unit-util.h b/src/shared/bus-unit-util.h
new file mode 100644
index 0000000000..55486f82ee
--- /dev/null
+++ b/src/shared/bus-unit-util.h
@@ -0,0 +1,27 @@
+#pragma once
+
+/***
+  This file is part of systemd.
+
+  Copyright 2016 Lennart Poettering
+
+  systemd is free software; you can redistribute it and/or modify it
+  under the terms of the GNU Lesser General Public License as published by
+  the Free Software Foundation; either version 2.1 of the License, or
+  (at your option) any later version.
+
+  systemd is distributed in the hope that it will be useful, but
+  WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+  Lesser General Public License for more details.
+
+  You should have received a copy of the GNU Lesser General Public License
+  along with systemd; If not, see <http://www.gnu.org/licenses/>.
+***/
+
+#include "sd-bus.h"
+
+#include "output-mode.h"
+#include "install.h"
+
+int unit_show_processes(sd_bus *bus, const char *unit, const char *cgroup_path, const char *prefix, unsigned n_columns, OutputFlags flags, sd_bus_error *error);